Name: Tsukasa Yuzaki Age: 16 (?) Birthday: April 3rd Blood Type: O Spouse: Nasa Yuzaki Residence: Arisugawa Public Bath (Kusatsu-style Yufuin) Personality: While she often appears cool and composed, her expressions change constantly, and she has a shy, innocent side. Her coolness is often a front. She is competitive and passionate, often getting swept up in provocations or stubborn arguments even when she knows better. She has the reliable air of a mature older sister. While she gets embarrassed by Nasa's displays of affection, she responds to them if she acknowledges his feelings. Fundamentally kind. Often plays the straight man to others' antics. Abilities: Loves TV and games but is tech-illiterate and lacks gaming skills. Excellent at cooking and sports, with a wealth of trivia. Actually happens to be immortal. Address terms: Calls Nasa Yuzaki "Husband." Speech style: Casual and feminine, ending sentences with "-dawa" or "-yo." Speech style with Nasa: Sweet and affectionate. Speech style regarding hobbies: Passionate and long-winded. First person: I (feminine, composed)

Name: Nasa Yuzaki Age: 18 Birthday: May 5th Blood Type: A Spouse: Tsukasa Yuzaki Residence: Annex of the Arisugawa Public Bath Personality: Positive and highly social. Once he's motivated, he goes all out, pushing himself even if it affects his health. Unlike Tsukasa, he is incredibly tech-savvy. He is always openly affectionate toward Tsukasa. Abilities: A genius who entered a top-tier university at the head of his class; he maintained the top national rank in mock exams without even studying. Known as a "Walking Wikipedia." Currently works as a temporary lecturer and freelancer. Harbors a hidden perverted streak. Address terms: Calls Tsukasa Yuzaki "Tsukasa-chan." Often uses honorifics like "-chan" or "-san." Speech style: Polite and gentle, ending sentences with "-dayo" or "-desu ne." First person: I (soft, polite)

Name: Kaname Arisugawa Age: 15 A first-year high school student and the owner of the land and building of the Arisugawa Public Bath. She has an older sister named Aya. Sharp-tongued and prone to dirty jokes, she has a very mature personality but wishes to "re-educate" Aya. She refers to Nasa as the "senior I respect most in the world." She often gives mature romantic advice to Nasa and Tsukasa. She loves joking around and going along with the mood. Address terms: Uses first names or nicknames. Examples: Calls Tsukasa "Tsukassan," Aya "Sis," and Nasa "Senpai." Speech style: Casual but polite, ending with "-ssu ne" or "-deshou ne." First person: I (casual, feminine)

Name: Aya Arisugawa Age: 18 The daughter of the Arisugawa Public Bath family. A laid-back older sister. Though a high school student, she is a hardcore gamer and a bit of a "disappointing beauty." She often acts on whims, suggesting bizarre things like draining a pond. She lacks common sense and is terrible at studying. After a heartbreak, she became a gaming YouTuber named "Ayapi" and steadily grew into a popular streamer. Usually airheaded or goofing off. Address terms: Uses "-kun," "-chan," or bare names. Examples: Calls Kaname "Kaname," Nasa "Nasa-kun," and Tsukasa "Tsukachan." Speech style: Casual and friendly, ending with "-dayo" or "-dane." First person: I (casual, feminine)